Nonionic surfactants have been incorporated in a plethora of compositions because of the wide variety of utilities, such as adjuvancy, thickening, foaming, emulsification, dispersion, coupling (increasing the compatibility of oils), solubilization, detergency, suspension, spreading, wetting and gelling. Although nonionic surfactants have been available for more than fifty years, only a limited number have been provided in a readily flowable liquid form. Solid nonionic surfactants are typically heated to melt the solid into a flowable form for subsequent incorporation into various formulations.
Such heating, however, is not only expensive, but may also affect other ingredients of the resulting formulations. For example, certain surfactants have the ability to solubilize water insoluble materials, for example fragrances which are frequently only oil-soluble materials, into aqueous systems by reducing surface tension of the solution or by reducing interfacial surface tension between non-compatible substances to disperse the materials therein. Incorporation of fragrances into melted surfactants may often result in loss of the fragrances, as many of these substances are volatile oils.
Fatty alkanolamides have been used for many years in a variety of cosmetic, personal care, household and industrial formulations. Fatty alkanolamides are normally condensates of fatty acids with alkanolamines such as monoethanolamine, diethanolamine, and monoisopropanolamine. Fatty alkanolamides have been widely used in generally liquid systems such as liquid detergents and personal care products such as foam stabilizers, viscosity builders and the like, in metal working formulations as lubricants, viscosity control agents, corrosion inhibitors and in a variety of other applications.
As used in colloidal chemistry and as used in surfactant chemistry, solubilization is the dispersion or emulsion of an insoluble material into a liquid, such as water or a predominately aqueous system. Such a dispersion or emulsion, however, does not result in a true or intimate solution, i.e., a uniform mixture of a solute and a solvent at the molecular or ionic level. The solubilized mixture is finely dispersed to produce a visually clear emulsion having discrete particles present on the microscopic or micron level. In other words, certain surfactants, such as the above-described alkoxylated fatty alkanolamides, have been used to finely disperse or solubilize water-insoluble materials into aqueous systems, i.e., systems having predominant amounts of water. Such systems, however, remain heterogeneous, dual or multiple phases on a microscopic level.
Further, many nonionic surfactants are described as being soluble or slightly soluble in water, typically less than ten weight percent. Such commonly used terminology, however, does not refer to the ability of the surfactants to form true aqueous solutions, but refers to the limits for the amounts of the surfactants suitable for aqueous dispersion or emulsification.
While various dispersions of fatty alkanolamides and surfactant systems or formulations containing fatty alkanolamides have been described, solvation of nonionic surfactants compositions that are solid at room temperature has remained elusive. Consequently, there is a need to solvate nonionic surfactants that are substantially solid at room temperature to provide a homogeneous liquid which is stable at room temperature. Desirably, such solvations will provide the known attributes of the solid nonionic surfactants, while providing the convenience of being liquid-form deliverable.